The present invention relates to an end wall for a winding roll which is rectangular, and preferably square with rounded corner surfaces. The end wall typically is comprised of a material which can be shaped without cutting. The front side of the end wall facing the winding roll forms a smooth, flat surface, and comprises a central push-in peg and locking bosses. The rear side of the end wall points outward away from the winding roll and is reinforced by radial and annular ribs. The end wall further comprises stacking bosses, which limit stacking pockets, on side walls which are at right angles to the front side and rear side. The stacking pockets have a shape complementary to that of the stacking bosses so that, during lateral stacking together, the stacking bosses and stacking pockets of one side wall can mutually engage without a gap with the stacking pockets and stacking bosses of one of the side walls of a further end wall.
An end wall of this type is known from U.S Pat. No. 4,884,690. An individual one-part end wall of this type can be made of plastic or of another material which can be shaped without cutting, for the packaging of winding material, (i.e. plastic films). The winding material is wound on wind-on tubes and the end wall forms, together with a second corresponding end wall, a dimensionally stable complete packaging of a winding roll.
From the known end wall described above, a number of vertically aligned end walls of ready-packaged winding rolls can be stacked with their side walls next to one another or above one another, as desired, and can be locked in engagement with one another or mutually. This means that winding rolls, ready-packaged by means of the end walls and tie-round bands, can be stacked above one another without further action. The ready-packaged winding rolls are conventionally stacked on wooden pallets. The end-wall side wall resting on the pallet has minimal frictional connection with the pallet, on account of the smooth surfaces of the bearing surfaces of the stacking bosses, and therefore the slip resistance of a stack of this type is not guaranteed. In particular, if heavy winding rolls having such end walls are packaged, in view of the small bearing surfaces of the stacking bosses on the pallet and the accompanying high specific surface pressure of the high surface load on the stacking bosses, there is an increased danger of breakage and a lack of stability of the side wall resting thereon.
German utility model 1,991,976 discloses a one-part end wall made of plastic, which consists of a four-cornered, preferably square, flat plate reinforced by radial webs. In the center is located a push-in peg for the winding-material roll and which is equipped, for example, with holding prisms. The plate is sheathed with a strap, on the outside of which small prism-shaped strips are arranged. The strap encloses, at the corners of the plate, four cup-shaped depressions, projecting into the free hollow space between the winding material and the packaging shell and open toward the outer end surface, and possesses a circumferential stop strip which is equipped with teeth.
German Offenlegungsschrift 1,486,562 discloses a protective packaging for film and metal rolls, which consists of two identical flanges equipped with a hollow hub which can be pushed into the winding core of the roll. Each of these flanges has at least two outer edges or edge parts which are beaded over parallel to one another and which are equipped with indentations and tongues. Thus, mutual engagement of the flange edges lying above one another is achieved during the packing of a plurality of rolls on one another, and mutual displacement of the stacked-up rolls is prevented. These flanges can, by means of their side walls, be stacked next to one another or above one another and brought into engagement only in a specific relative arrangement.
Square end walls for winding rolls are described in GB Patent Specification 1,497,929, which also discloses flanges present at right angles to the end wall and along each side edge of an end wall. One of the four circumferential flanges has two projecting pegs, whereas the opposite flange possesses two holes at the locations which correspond to the locations of the pegs. The stacking of the winding rolls takes place in rows, the upper row of winding rolls being offset with their end walls relative to the lower roll, in such a way that the pegs of one end wall are in engagement with the holes of two adjacent end walls located underneath. The result is that lateral displacement of the two rows of winding rolls relative to one another is prevented.
In the end walls described in the prior art, it is considered a disadvantage that, although the end walls without a winding roll can be stacked above one another with further horizontally aligned end walls, the vertically aligned end walls, especially with the winding rolls, can be stacked next to one another or above one another and brought into engagement with one another only in a specific relative arrangement because of the arrangement of their side walls. The result is that ready-packaged winding rolls cannot be closely stacked above one another in a simple and reliable way without further manipulation.